PROJECT SUMMARY The mammalian brain is arguably the most complex biological structure. Investigating cellular functions and mapping neural connections in the brain are critical tasks to better understand the brain in health and disease. This is particularly challenging in vivo due to the inherent limitations in experimental latitude and simultaneous access to multiple brain regions within the same animal. These shortcomings hinder multimodal interrogation of multi-synaptic circuits and mesoscale connectomics. Of particular importance, these experimental inadequacies grow in proportion to the complexity of the brain and cranial anatomy, impeding translation to larger mammals. This grant addresses these tasks by optimizing and validating a first-in-class neurotechnology called BrainEx for the restoration of molecular and cellular functions of the postmortem large mammalian brain under ex vivo, normothermic conditions. We specifically propose to continue optimizing BrainEx in porcine brains, while validating the efficacy of the BrainEx system as a new experimental platform for electrophysiological, connectomic, and imaging studies in the fully isolated, intact, and functional large mammalian brain. There are four major distinguishing aspects of this application: (1) implementation of novel approaches developed to restore cerebral macro- and microcirculation and extend cellular viability of the postmortem brain under normothermic conditions such that researchers can (2) simultaneously trace connections and characterize cellular function and morphology by chemical and vector-based techniques across myriad brain regions, including areas inaccessible to in vivo surgical approaches; (3) investigate multisynaptic long-range circuitry and cortical network electrical activity; and (4) perform functional PET and CT imaging studies in the ex vivo large mammalian brain. This methodology represents a new tool for more thorough investigation of the structure and function of complex circuits and the cells within them. Wide distribution of this technology will grant investigators experimental advantages across species not afforded by tissue culture or in vivo approaches.